This invention relates to elastomeric materials and specifically to elastomeric laminates and composites. These materials are particularly useful in applications such as headbands for respirators and masks.
Elastomeric materials are widely used in applications such as baby diapers and adult incontinence devices. These materials are typically used in the body hugging portions of the garments. For example, U.S. Pat. No. 4,681,580 to Reising et al. and U.S. Pat. No. 4,710,189 to Lash describe the use of such material in diapers. Materials of this nature are described in more detail in U.S. Pat. No. 3,819,401 to Massengale et al., U.S. Pat. No. 3,912,565 to Koch et al., U.S. Pat. No. RE 28,688 to Cook, and U.S. Pat. No. 4,820,590 to Hodgson et al.
A difficulty in using elastomers for other applications, such as headbands, is that they typically exhibit relatively inflexible stress/strain characteristics. Materials with a high modulus of elasticity are uncomfortable for the wearer. Problems with a relatively stiff or high modulus of elasticity material can be exaggerated by the coefficient of friction and necking of the elastomer which can cause the material to bite or grab the wearer.
In mask and respirator applications, the comfort of the wearer is important. The masks and respirators may be worn for long periods of time. Accordingly, the headbands should be smooth and soft. However, in order to facilitate a good seal between the mask or respirator and the wearer""s head, the surface of the headband should not be slippery. Headbands can slip because of the weight of the respirator or mask and the force exerted by the stretched headband when it is placed over the head of the wearer.
Oil and heat pose another problem with respect to headband applications. Humans excrete oil from skin. The headband comes into contact with this oil along the wearer""s face and hair. Oil, in combination with heat, may cause the degradation of many materials that would otherwise be suitable for use in headbands.
Accordingly, there is a need for elastomeric laminates and composites that provide a soft and smooth feel yet exhibit non-slip characteristics.
In addition, there is a need for oil resistant elastomeric laminates and composites that are suitable for use in headbands.
The present invention relates to composite and laminate materials that are soft and smooth to the touch yet exhibit non-slip characteristics. The materials have at least one discrete elastomeric core material, in the form of a layer or region, and at least one skin layer. The core comprises a thermoplastic and extrudable polymer such as a xe2x80x9cKRATONxe2x80x9d polymer sold by Shell Chemical Company of Beaupre, Ohio. This core provides elastomeric properties to the material.
The polymeric skin layer comprises a semi-crystalline or amorphous polymer and an elastomeric block copolymer or pressure sensitive adhesive, the combination of which is less elastic than the core layer(s) and will undergo permanent deformation at the stretch percentage that the elastomeric laminate will undergo. The friction force of this skin against a surface may be altered by adjusting the blend of polymer and block copolymer or pressure sensitive adhesive. The polymeric skin layer(s) is also capable of becoming microtextured such that the surface comprises peak and valley irregularities or folds that are large enough to be perceived by the unaided human eye but are small enough to be perceived as smooth or soft to the touch. This layer can function to permit controlled release or recovery of the stretched elastomer, modify the modulus of elasticity of the elastomeric material, and/or stabilize the shape of the material.
Increased oil resistance may be achieved in the present invention with the addition of an oil resistance agent into the core layer. In a preferred embodiment, the oil resistance agent is poly(phenylene oxide). Other oil resistance additives may added to increase oil resistance.
The material of the present invention is well suited to applications where comfort is enhanced by a smooth and soft touch and safety may be enhanced by a non-slip surface. Such applications include headbands for respiratory devices such as respirators, surgical masks, clean room masks, face shields, dust masks and a variety of other face coverings.